(1) Field of the Invention
The invention pertains to the fields of measuring distances with lasers, and position and orientation sensors, such as accelerometers and gyroscopes. It also deals with calculating distances and positions by geometric means. The invention is also related to a technique known as simultaneous localization and mapping (SLAM), which is used by robots and autonomous vehicles to build up a map within an unknown environment.
(2) Utility of the Invention
Distance and size measuring is an essential activity for a multitude of tasks, including planning, estimation, construction, layout, etc. A means of making measurements easier and quicker to perform would be of obvious benefit for these tasks. Currently, this is done either by placing a measuring device such as a tape measure over the span to be measured, or by use of a distance measuring device such as a laser directed at a point to determine the distance from the point to the device. This invention is distinctive in that it allows a user to target two endpoints successively with a laser beam from different vantage points and have the distance and relative coordinates calculated by tracking intervening position and orientation changes of the device.
(3) Feasibility of the Invention
Position and orientation sensors such as accelerometers and gyroscopes have become commonplace and affordable components of other devices. For example, it is common for smart phones to contain accelerometers to assist with orienting the screen depending on a user's handling of the phone, and as inputs to mobile gaming applications. In the realm of tools, accelerometers are used to track angular movements to align a tool to a work piece, for example. The precision of these sensors is improving constantly as the cost drops, making them attractive components for motion-based devices such as the invention described herein.
(4) Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98. Related Art    a) SYSTEM AND METHOD FOR ORIENTATION AND LOCATION CALIBRATION FOR IMAGE SENSORS, Germain et al., Pub. No.: US 2008/0306708 A1, Dec. 11, 2008.
Synopsis:                This is a system employing position measurement sensors and point sources of light to determine the location and orientation of video cameras in a simulation arena environment. The location of a camera is determined by measuring the distance from the camera to at least two known points, where the known points may be point sources of light, other cameras, or a combination thereof.        
Comparison with the Current Invention:                In the above invention, known fixed target points are used to determine camera position; there are no laser distance measuring components in the system. In contrast, the current invention relies on a laser distance measuring component to target and measure endpoints arbitrarily located in space.            b) METHOD FOR CALIBRATING A CAMERA-LASER-UNIT IN RESPECT TO A CALIBRATION-OBJECT, Karabassi et al., US007564571B2, U.S. Pat. No. 7,564,571 B2, Jul. 21, 2009.
Synopsis:                The invention refers to a method for calibrating a camera laser-unit with respect to at least one calibration-object disposed at a given position and orientation in a three dimensional space. The method has the advantage that the same calibration-object can be used for the calibration of the camera and of the laser.        
Comparison with the Current Invention:                The above invention is about locating the camera laser-unit using a fixed calibration-object as a target. The calibration-object must have a specific shape and markings to allow the camera to compute the location using the image of the calibration-object while the laser targets it. This is not a laser distance measurement as defined in the current invention. Furthermore, the location of the device is not the goal of the current invention; rather the goal is the location and distances spanning arbitrarily located endpoints.        
c) MACHINE VISION METHODS USING FEEDBACK TO DETERMINE CALIBRATION LOCATIONS OF MULTIPLE CAMERAS THAT IMAGE A COMMON OBJECT, Wallack et al., U.S. Pat. No. 5,978,521, Nov. 2, 1999.
Synopsis:                The invention provides improved machine vision methods for determining a calibration relationship among the imaging reference frames of multiple cameras that acquire images of a common moveable object. The calibration relationship includes parameters for transforming positional coordinates among the camera's respective imaging reference frames. The method includes placing on the common object a plurality of calibration marks that are at known positions relative to each other with respect to a frame of reference; aligning an axis of the reference frame with an axis of the object's reference frame of motion, i.e., the reference frame in which the object moves; placing a respective mark in the field of view of each camera; determining a calibration relationship among the imaging reference frames of the respective image acquisition devices as a function of the known relative locations of the marks, (ii) the mark positions determined for each camera, and (iii) the object calibrating positions determined for each respective image acquisition device.        
Comparison with the Current Invention:                The above invention has fixed cameras viewing a moveable object that is marked with special calibrations that allow the cameras to fix the position of the object in space. In the current invention, neither the device nor the targets are fixed in space. Also, the target endpoints are not marked in any special way. Finally, there is no laser measuring device as defined in the current invention.            d) METHOD FOR DETERMINING POSITION, LASER BEAM DETECTOR AND DETECTOR-REFLECTOR DEVICE FOR A SYSTEM FOR DETERMINING POSITION, Petschko et al., Pub. No.: US 2010/0302557 A1, Dec. 2, 2010.
Synopsis:                The invention relates to a system for determining a position by emitting a laser beam by a laser source positioned in a reference system onto a detector and simultaneously detecting the laser beam by its impingement on a detector that is configured with a plurality of discrete partial detection areas, thus defining an emission direction of the laser.        
Comparison with the Current Invention:                The above invention requires the use of a specially configured target component. It also does not use a laser distance measuring device as defined in the current invention.            e) HIGH SPEED SCANNING METHOD AND APPARATUS, Steven J. White, U.S. Pat. No. 4,498,778, Feb. 12, 1985.
Synopsis:                This invention is an apparatus for determining the spatial coordinates of a workpiece on a precisely formed jig using a planar light source and a camera adapted to view the intersection of the planar light with the jig and the workpiece. The form of the jig is detected by the camera and used to compute the coordinates of the workpiece.        
Comparison with the Current Invention:                In the above invention, the signal and detection system are at fixed position relative to the target. There is also the special form of the jig to allow video analysis of its image. There also is no second target involved. It also does not use a laser distance measuring device as defined in the current invention.            f) CONTOUR LINE SCANNER, Earl D. Jenks, Publication number U.S. Pat. No. 4,541,722 A, Sep. 17, 1985.
Synopsis:                This invention uses lasers to project contour lines of light upon lumber to allow the most cost-effective cutting of boards. A TV camera detects the contour lines and converts the image into information to control the milling of the lumber.        
Comparison with the Current Invention:                Unlike the current invention the above invention uses fixed position devices: the lasers and TV. It also does not use a laser distance measuring device as defined in the current invention.        